The present invention relates to an optical transmission process by wavelength shifting and to a corresponding system. It is used in optical telecommunications.
Semiconductor lasers are well suited to optical telecommunications more particularly due to the possibility which they offer of carrying out amplitude, phase or frequency modulations.
Recently, multisection semiconductor lasers have appeared, which make it possible to further improve these methods.
Thus, an optical transmission process is known utilizing frequency shift keying (FSK), which uses a laser having two sections. Such a process is e.g. described in the article by H. KOBRINSKI et al entitled "Fast Wavelength Switching and Simultaneous FSK Modulation Using Tunable DBR Laser" and published in the journal "Electron. Lett.", 1990, 26, pp 308-310.
It is also known that these multielectrode structures, when they are of the distributed feedback (DFB) type, can be used for switching, in the manner described in the article by H. SHOJI et al entitled "New Bistable Wavelength Switching Device Using a Two-Electrode Distributed Feedback Laser" and published in the journal "Electron. Lett., 1988, 24, pp 888-889. These structures can also be used for producing logic circuits, as described in the article by K.Y. LIOU et al entitled "Electro-Optical Logic Operations with Two-Electrode Distributed Feedback Injections Laser" and published in the journal "Appl. Phys. Lett.", 1989, 51, pp 1777-1779.
In addition, an addressing method by switching between several wavelengths of the same double-section DFB laser was described by J. M. COOPER et al in an article entitled "Nanosecond Tunable Double-Section DFB Laser for Dynamic Wavelength Addressing Applications", published in the journal "Electron Lett.", 1988, 24, pp 1237-1239.